Electric cut-out



April 26, 1927. 1,626,462-

c. HALL ELECTRIC CUT-OUT Filed Aug. 8, 1924 Inventor: ChesterLJfiaH,

His Aitorneyp a top view ofthe cut-out shown in "Figs. 3 and 4 are detail views showing the construction of certain parts ofthe cut-out Patented Apr. 26, 1927.

UNITED STATES PATENT OFFICE.

CHESTER I. HALL, OF FORT WAYNE, INDIANA, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC CUT-OUT.

Application filed August 8, 1924. Serial No. 730,984.

My invention relates to electric cut-outs, particularly enclosed thermal responsive electric cutouts which are provided with terminals for electrically connecting and mechanically supporting the cut-outs in a socket, receptacle, or the like.

The object of the invention is to provide an improved form of thermal responsive cutout of the above type which will afford efficient time delay overload protection to small electric motors and the like. Among the advantages obtainable in connection with my invention I may mention simplicity and ruggedness of construction, ease and cheap ness in manufacture, practical effectiveness and the total absence of any parts needing replacement in ordinary service. Cut-outs constructed in accordance with my inventlon are specially suitable for motors and other apparatus whose capacity for enduring overload and other conditions of current flow without injury. depends upon the duration of the abnormal current as well as on its absolute magnitude. The invention itself, comprising various novel features and details and combinations and arrangements of parts, is set forth in the following description of a preferred form of cut-out which embodies the invention, and the scope of the invention is indicated in, the appended claims.

In the accompanying drawing, Fig.- 1 is a mid'sectional view of a cut-out constructed in accordance with my'invention, Fi 2 is 1g. 1,

illustrated in Fig. 1, and Big. 5 is a diagrammatic view showing the cut-out, in use.

- connected as well as mechanically supported in an ordinary t pe of Edison screw socket or receptacle. ithin the enclosing haw 10,

the circuit controlling members comprising the bimetallic thermoresponsive element 13 and the spring contact 14 .are disposed in cooperating relation as shown. 7 4

It will be seen that the bimetallic element 13 is bent atone end andis secured at the other end to the support 15 which is 841-.

justably mounted in the base -by means of the compression spring 16 and the screw 17 which latter extends through a slot in one side of base 10 with the head thereof conveniently accessible. The spring contact 14 is suitably connected at one end to the screw shell 11, it being riveted as shown, and ex tends through an opening in the base 10 with the other end biased to the circuit opening position indicated by the dotted lines in Fig. 1. The upper end of the spring contact 14 is arranged to be flexed into circuit closing engagement with the bent end of thermoresponsive element 13 as shown in full lines in Figs. 1 and 2. The upper end of spring contact 14 preferably is bifurcated as better shown in Fig. 3, so as to straddle the thermoresponsive element 13'and thereby insure that the bent end of the latter is always brought into latching relation with the central part of the spring contact when the same is flexed to the left from its biased position, indicated in the drawing. The upstanding ears at the end of spring contact 14 also form a convenient means for manually flexing the same into latching engagement with the thermal element 13.

As shown in Figs. 1 and 4, a hood 18 of insulating material is mounted upon the upper end of support and enshrouds all except the bent down end portion of thermoresponsive element 13 and thus prevents arcing between the spring contact 14 and the thermoresponsive element 13 as well as accidental contact between the same when the spring contact occupies the position indicated by the dotted lines.

In order to heat the thermoresponsive element 13 so as to effect an upward move ment of the free end thereof and release the spring contact 14, and thereby permit the latter to snap into the circuit opening posi tion, av heatng coil 19 is disposed in intimate' thermal relation with the support 15 and electrically connected between the center contact 12 and the support 15 as shown.

The base 10 may be provided with a removable cover 20 which has a transparent central portion as illustrated in Fig. 2if desired. This permits the operating relation of the spring contact 14 and the thermoresponsive element 13 tobe observed conveniently. p 7

' In Fig. -5, I have diagrammatically illustrated myinvention applied to protect an electric translating device, such as the three phase alternating current electric' motor shown, from continued overload current. As shown, the motor 21 is connected to the three phase supply lines 22 with the ordinary safety fuses 23 and the thermal cut-outs 24 like that shown in Fig. 1 interposed in two of its leads. The fuses 23 can safely be rei lied on against short circuits or extremely heavy overloads but it is often possible for the motor to be subjected to currents which are not excessive enough to blow the fuses 23 yet which if long enough continued will injure or even destroy the motor insulation by prolonged overheating, such being the case particularly when one of the fuses 23 blows and the motor .21 continues to run single phase. In some cases also, it may be desirable to allow the motor 21 to be subjected toexcessive current for limited periods as at starting or under special conditions of use if only it can be insured that no such current shall continue long enough to be injurious. It will be apparent that with the cut-outs shown in Fig, 1. an appreciable interval of time will be required for heat to be transmitted from the heating coil 19 through the support 15 to the thermoresponsive element 13 upon the. occurrence of overload conditions. By a proper design of the heating coil 19, as well as the other parts, it is possible to make the heating characteristics of the cut-outs duplicate those of the motor with which it is intended to be used, and thus insure that the cut-out will always act before any injurious heating can occur, no matter how light or how heavy the overload' on the motor. At the same time, it is possible to allow operation of the motor to be continued for a reasonable time under an overload it can safely endure.

y reason of the adjustable mounting of the support 15 and hence of the thermal responsive element 13 carried thereby, the position of the free end of the latter with respect to the spring contact 14 may be varied easily and conveniently so as to effect the opening of the cut-out responsively to the heating effect of different values of current through the heating coil 19.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention together the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is, 1. A thermal electric cut-out comprising an enclosing base. a pair of terminals secured to said base. a support of heat conducting material mounted within said base,

a movable bi-mctallic thermal responsive element having one end secured to said support and electrically connected to one of said terminals to be heated in accordance with the current in the circuit controlled by the cut-out, a spring contact secured to said base and electrically connected to the other of said terminals, said contact being arranged to be flexed into latching engagement with the free end of said element to complete a circuit between said terminals, and an electrical heater connected in said circuit for heating said support to supply heat to said thermal responsive element and thereby cause the free end of said thermalelement to move and thereby release said spring contact member.

2. A thermal cut-out comprising an on closing base of insulating material having a screw shell terminal and a center terminal, a support of heat conducting material, means for adjustably securing said support within said base, a bi-metallic thermal responsive element secured at one end of said support and extending therefrom, an insulating hood mounted at said end of said support for enshrouding a portion of said element, an electrical heater surrounding an intermediate portion of said support and electrically connecting the said thermal element with one of said terminals, a spring contact member mechanically secured and electrically connected to the other of said terminals at one end and arranged to be flexed into mechanical and electrical engagen'ient with the said thern'ial element to complete a circuit between said terminals. In witness whereof, I have hereunto set my hand this 4th day of August, 1924.

CHESTER I. HALL. 

